Mining machine undercutter



J. D. WEST MINING MACHINE UNDERCUTTER July 20, 1954 7 Sheets-Sheet 1 Filed June 29, 1949 l INVENTOR. (lb/21a fl. II Z'si w u m m w m July 20, 1954 J. D. WEST MINING MACHINE UNDERCUTTER 7 Sheets-Sheet 2 Filed June 29, 1949 h Ln.

A TTUENEYS y 20, 1954 J. D. WEST MINING MACHINE UNDERCUTTER Filed June 29, 1949 7 Sheets-Sheet 3 y 20, 1954 J. D. WEST MINING MACHINE UNDERCUTTER 7 Sheets-Sheet 4 Filed June 29, 1949 y 1954 J. D. WEST MINING MACHINE UNDERCUTTER 7 Sheets-Sheet 5 Filed June 29, 1949 July 20, 1954 Filed June 29, 1949 J. D. WEST MINING MACHINE UNDERCUTTER '7 Sheets-Sheet 6 INVENTOR.

amgyzfw/ A TTDP/VEVS July 20, 1954 Filed June 29, 1949 .J. D. WEST 2,684,234

MINING MACHINEUNDERCUTTER 7 Sheets-Sheet 7 Patented July 20, 1954 MINING MACHINE UNDERCUTTER John D. West, Manitowcc, Wis, assignor to Safeway Mining Machine Company, Chicago, 111., a corporation of Delaware Application June 29, 1949, Serial No. 102,103

14 Claims.

This invention relates to mining machines and particularly to an undercutting mechanism to cut a kerf across a portion of the working face of a vein of mineral material and means to facilitate breaking down material over said kerf.

It is desirable, in mining operations, to loosen and remove mineral material from its natural location as nearly continuously as possible and many attempts have heretofore been made to provide machines to cut and remove such material, particularly coal, without the necessity of undercutting, drilling, shooting, and removing the loosened material. In general, this invention relates to the type of machine adapted to loosen and remove coal or the like without the necessity of using explosives. The invention is directed particularly to means for cutting the horizontal kerf in the mineral working face in advance of breakdown means adapted to loosen the material above the kerf so cut. The present invention constitutes an improvement of the machine described and claimed in copending application Serial No. 25,015, filed May 4 1948, in the name of George A. Merchant, now Patent No. 2,531,072. According to the disclosure in that application, the breaking down means consists of a plurality of picks orbitally movable in vertical planes to break down material above an undercut kerf. During the breaking down operation the machines tends to rise off the floor of the mine but the machine is so designed that a portion of the frame thereof engages a horizontal kerf, continuously out in advance of the breaking down means, to prevent such rising. The present invention incorporates improvements therein in the undercutting and breaking down means and contemplates an improved conveyor mechanism for receiving broken down mineral and conveying it toward the rear of the ma chine.

The undercutting mechanism of the present invention comprises orbitally movable cutter heads movable in closed orbits in a horizontal plane adjacent the floor of the mine. These heads constitute the foremost portions of the machine and extend forwardly considerably in advance of the breaking down means. At least two such heads are provided and are mounted adjacent the sides of the machine so that their cutting movement takes place inwardly toward the center line of the machine. The improved hold-down means comprises a plate extending laterally across the machine and over portions of the undercutters and includes a rearwardly directed step over which mineral material is adapted to extend to facilitate breaking by the downwardly movable breaking-down means heretofore mentioned.

It is an object of this invention to provide an undercutter for a mining machine capable of cutting a continuous kerf extending transversely across the entire Working face of the mineral material and of a slightly greater width than the transverse dimensions of the machine itself.

It is also an object of this invention to provide an undercutting mechanism adapted to move out material from the kerf progressively inwardly and rearwardly of the machine to a conveyor.

It is another object of this invention to provide an undercutting mechanism incorporating pushing means to move material cut thereby toward a conveyor.

It is a still further object of this invention to provide an undercutting mechanism having holddown means to prevent rising of a mining machine therein said hold-down means are of new and improved construction.

It is a further object of this invention to provide, in a mining machine of the type disclosed, auxiliary conveyor means to receive broken: down material and move the same rearwardly and inwardly toward a main conveyor.

Another object of the invention is to provide an undercutting mechanism wherein the drive means are completely enclosed and thus protected from dust and grit and wherein the working parts are compactly arranged and of unusual strength and ruggedness.

Additional objects and advantages will appear as the description proceeds in connection with the accompanying drawings wherein:

Fig. 1 is a side elevation View of a mining machine incorporating the present invention, parts of the machine being broken away.

Fig. 2 is a plan View of the undercutter shown in Fig. 1 and comprises that portion of the machine extending forwardly from the endless treads of the supporting carriage.

Figs. 4 and 5 are plan views of one of the cutter heads, showing the same in various positions of movement about its orbital path,the top or hold-down plate being removed and portions of the frame being shown in section. V g I Fig. 6 is a vertical sectional view taken substantially along the line 6-5 of 4, and showing a portion of a conveyor.

Fig. 7 is a vertical sectional view taken substantially along the line 71 of Fig. 2 and showing the parts on an enlarged scale.

Fig. 8 is a sectional view taken substantially along the line 88 of Fig. 2 and also showing the on an enlarged scale.

Fig. 9 is an enlarged sectional view taken substantially along the line 55-43 of Fig. 3.

Fig. 10 is a fragmentary sectional View taken along the line l@!0 of Fig. 2, and

Fig. 11 is a perspective view of a plurality of links of the auxiliary or apron conveyors, show ing the manner in which the links are interengaged to form a substantially continuous con veyor surface.

The undercutting mechanism of the present invention is particularly adapted for use with a mining machine of the type disclosed in the above-identified copending application and is intended to replace all portions thereof extending forwardly of the endless treads shown therein. The main portion of the machine, comprising the carriage 2, conveyor 3, and breakdown mechanism t will not be described in detail since it is adequately disclosed in the copending application referred to. However, it will be stated that the main frame 6 of the machine supports an auxiliary frame 8 for pivotal movement about an axis 9. The auxiliary frame 8 in turn supports a shaft it having a plurality of eccentrics H mounted thereon. Each eccentric is engaged with a movable pick head it having a pair of groups of pick points it and Ed vertically spaced thereon and being guided at their rearmost ends by swinging links 56. Suitable drive means transmit power to the shaft Hi and cause it to rotate in such direction that the pick points i3 and it are caused to move forwardly and downwardly in engagement with the mineral face, then backwardly and upwardly to again move into engagement with the mineral and downwardly in breaking down movement. The movement of the pick points l3 and it may be described as orbital in that it follows a continuous closed path somewhat oval in shape.

The undercutting mechanism of the present invention is carried as a forward extension of the main frame 6 and includes a horizontally extending upper plate 6i engageable with the downwardly facing surface of the kerf out by the m chanism. The plate fill terminates in a transverse laterally extending terminal edge Zll positioned rearwardly of the undercutting means but forwardly of the lowermost position of the break ,1

ing down picks M. It will thus be seen that as the machine advances into the mineral material, the plate Ell and step 2t will be in advance of the rearwardly extending portions 22 of the uncut mineral material. down picks it move downwardly in a cutting cycle and approach the lowermost portion of their paths, the overhanging material 2| may be readily broken from the mineral face since the edge 2% will constitute somewhat of a fulcrum for the said material rearwardly of which it is unsupported.

Although shown in connection with the machine described in the identified copending appli cation, it is to be understood that the undercutting mechanism of the present invention is not to be so limited but may be employed with other mining machines having means for breaking down material above an undercut kerf.

Referring now particularly to Figs. 2, 3-5 and 6, the forward portion of the main frame of the mining machine may comprise forwardly extending rigid frame members 22 (Figs. 2 and 6), a bottom plate 2 3 and a top or upper plate 26. A central conveyor chain 23 extends over a sprock- When the breakinget 29 mounted on a transverse shaft t l (Fig. 6) and carries spaced conveyor flights pivoted as at 33 to the chain 23. The flights are spaced longitudinally of the chain and during operation of the conveyor the bottom flights move forwardly above the bottom plate 24, then upwardly over the sprockets 29 and rearwardly along the top of the upper plate 26. Material resting on the upper plate 26 will be engaged by the flights 32 and moved rearwardly of the machine to a suitable discharge position.

The shaft 39 has pairs of sprockets outwardly of the sprocket 29 and about which apron conveyors 35 are trained. The apron conveyors 35 will be described in greater detail later.

The lowermost plate 2% of the main frame e3;- tends forwardly of the shaft 36 and its laterally outermost edge portions 38 (Fig. i) extend forwardly a greater distance than the intermediate portion. Vertically arranged frame members dd, 42, 43 and M are welded or otherwise rigidly attached to the bottom plate 24 and form therebetween an elongated hollow housing The members d2 terminate at their rearmost ends a short distance behind the forward edge ll of the bottom plate 2 and transverse vertical members it are welded or otherwise rigidly attached to the bottom plate 2 and to the rearmost end of the member &2. The members at extend inwardly toward the longitudinal center line of the machine but terminate short of said center line adjacent the rearmost edge of a vertically extending plate member 50. Additional vertical members 5! further rigidify the structure and form continuations of the housings id.

The undercutting means are supported by and driven through housings 52, which are reverse duplicates of each other and only one of which will be described in detail. Each housing comprises upper and lower sections 53 and (see Figs. 6 and 9) bolted or otherwise secured together to form a unitary hollow housing. Each of the housings 52 has a rearwardly exten g arm 55 (Fig. 4) terminating in a bracket or rl 56 attached to the vertical frame member by cap screws El or in any other sui able ner. A coupling member 55 is bolted or otherwise rigidly attached to the inner of the frame plate at and to a portion 59 of the ho ing 52. In this manner the housings are rigidly and fixedly attached to the main frame of the machine at longitudinally spaced points, thus insuring efficient bracing and rigidity to withstand the stresses to which they are subject.

The vertical frame members defining the housings 66, and the forwardly extending side portions of the bottom plate 24 thus constitute for wardly extending portions of the main frame of the machine and define the lateral extremities of the machine. Extending transversely across the mining machine and across the tops of; the forwardly extending housings 66 is the upper plate 60. This plate constitutes a closure for the tops of the housings it and defines the upper surface of that portion of the undercutter adapted to enter the kerf cut in the mineral face. A portion of the plate so defines the terminal edge 20, previously referred to, and as clearly shown in Fig. 2, that terminal edge extends transversely of the machine between the housings 36.

The upper sections 53 of the housings 52 provided with inwardly extending projecting portions 62 (see also Fig. 9) terminating in attachment portions 63. The plate Gil has attached thereto on the under side thereof, a pair of bosses 64, laterally spaced on opposite sides of the 1ongitudinal center line of the machine and vertically aligned with the portions 63 of the upper housing members 53. A bolt 65, or other suitable fastening means, passes through the member 63 and the bosses 85 to rigidly attach the extension 52 to the top plate til. Thus, the housings- 52 are rigidly attached to the main frame of the machine at three horizontally spaced points which results in an extremely rigid structure capable of withstanding the high stresses resulting from the operation of the undercutter.

A vertical brace 66 (see Figs. 2, 4 and in the form of a fiat plate-like structure arranged vertically, extends from the bottom plate 24 to the top plate 60 and constitutes additional bracing means for the said top plate. A reinforcing member 6'2 extends beneath the rcarrnost edge of the plate 693 to add strength thereto at the step or edge 2d and constitutes a bearing between the plate ti? and the brace 66. A. second plate 68 extends across the machine and defines a surface somewhat belowthe top surface of the plate 543 immediately to the rear of the step 23. The plate $3 extends entirely across the machine and rearwardly to a terminal edge 69 spaced forwardly of the shaft 36 and the central conveyor driven thereby at its central portion. The end portions of the plate 58 extend rearwardly to the frame plates 28, which are closely adjacent the forward ends of the apron conveyors 35. The plate 68 is provided with a transverse edge-reinforcing member I0 at its central portion. The plate 68 also rests upon the brace 66 and may be rigidly attached thereto. As clearly shown in Fig. 10, the brace 66 is of limited fore and aft extent and is chamfered or bevelled at its forward edge to reduce the resistance to movement of mineral material therearound.

Suitable ribs I2 or other reinforcing means are attached to the under-surface of the plates 69 and G8 and extend from the bosses 64 inwardly and rearwardly to the brace 66.

The connecting member 58 (see Fig. 9) is of generally cylindrical configuration and hollow and is provided at its outermost end with a suit able seat for an anti-friction bearing M. The mating sections of the housing 52 provide a seat for an inner anti-friction bearing I5. A shaft I'd is mounted for rotation in the bearing I5 and carries a bevel pinion I? at its inner end, within the hollow interior of the housing 52. The outermost end of the shaft 76 is splined or otherwise formed to drivingly engage a sprocket IS. The sprocket it is within the housing 45, previously described and has a hub portion l9 extending into the connecting member 58. The hub 19 is rotatably supported by the bearing I4. If desired, the shaft it may be provided with a threaded end portion til and a nut ill may be employed to hold the sprocket F3 in position on the shaft "I6. Suitable dust sealing means 82 are preferably provided outwardly of the bearing M to prevent entry of dust or other foreign material into the interior of the housing 52.

Sprocket chains 64 (Fig. 2) are trained over the sprockets l8 and over sprockets 86, mounted on the ends of the transverse shaft 30 previously described. Thus the shafts 76 are connected to and driven by the shaft 30.

Referring again to Fig. 9, the upper and lower sections and 5d of the housing 52 are provided with aligned openings defining seats for anti-friction bearings 28 and 89. The bearings 88 and 89 mount a hollow shaft 90 for rotation on a vertical axis in the housing 52. The hollow shaft is provided with a flange 9I to which a bevel gear 92 is riveted, bolted, or otherwise suitably attached. The bevel gear 92 is arranged to mesh with the bevel pinion 'I'I whereby rotation of the shaft I6 will cause the hollow shaft 90 to rotate about its axis. The shaft 9% terminates at its ends short of the outer surfaces of the housing 52 and is provided with internal keyways. A pair of cranks 534 have inwardly extend ing hubs extending into the hollow shaft 95. The hubs 95 are suitably keyed to the shaft 9t and are arranged to extend with the throw of one crank in alignment with the throw of the other crank. The cranks 94 and hubs 95 are provided with a central bore to accommodate a bolt or the like 96 by which the cranks and the shaft 96 are held in assembled relationship. The cranks 94 rotate in parallel horizontal planes above and below the housing 52 and are provided with suitable bearing seats for anti-friction bearings I00. The anti-friction bearings we have their axes in vertical alignment and eccentric to the axis of the shaft 92'] and the hubs 95. The anti-friction bearings I01! rotatably connect the cranks 94 to intermediate portions of a pair of arms I02 and N33, to be described later. Dust seals Iild, of suitable design, are arranged between the cranks 94 and the arms I02 and M3. The dust seals are circular and extend concentrically about the anti-friction bearings iIlii at such radius as to encompass the ends of the bolt 96. The bearings I08 are thus sealed against the entry of dust, grit and the like. Additional dust seals IilI are arranged between the cranks 9c and the housing 52 to protect the bearings 83 and 89 and the gears within the housing.

Referring now to Figs. 4 and 6, the arms Hi2 and I03 extend generally forwardly from their connection with the cranks 94 and are attached, at their forward ends, to an undercutter head I Ill. The arms I02 and I03 may be bolted or otherwise securely fastened to the head fill at the top and bottom thereof. As clearly evident from Fig. 6, the uppermost surfaces of the arms I82 are substantially flush with the uppermost surface of the head IIfl which latter surface is substantially coplanar with the upper surface of the plate 61' heretofore described. The portion of the arm I92 extending rearwardly from the head II!) is below the upper surface of the plate til at sufiicient distance to pass under the plate with suitable working clearance therebetween. In like manner, the lowermost surface of the arm Hi3 is spaced slightly above the bottom surface of the plate 24.

The undercutter head III) is of considerable lateral extent, transversely of the machine ant. is formed with a plurality of forwardly projecting portions III, II2 and I I3. Each of the projecting portions is provided with a plurality of sockets H4 adapted to receive the shanks i 55 of suitable pick points.

The picks are arranged in a plurality of groups II 6, II! and H8. Suitable set screws I253 may be arranged to clamp the pick points in their respective sockets. The pick points in each group are arranged with their tips lying in the vertical plane, but the uppermost and lowermost pick points are spaced outwardly of the points nearer the vertically central portion of the undercutter head. Thus, the pick points of each group are arranged in V formation with the apex of the formation pointed inwardly toward the center of the machine. By this arrangement the center point of each group' makes a first cut and the other points of that group are enabled to cut mineral material into the groove formed by the leading pick. The action is in the nature of undercutting the material for each succeeding pick point. As evident from Figs. 6 and 7, the axes of the pick points diverge forwardly in a vertical plane whereby the tips of the uppermost and lowermost picks are located respectively above and below the top and bottom surfaces of the heads iii). By this arrangement the picks out a kerf having a vertical dimension somewhat greater than that of the head lit and suificient for the spaced plates 24 and St to enter the keri with suitable working clearances.

The arms Hi2 and H33 extend rearwardly beyond their connection to the cranks 9 1 (see Fig. 6) and terminate at their rear ends in aligned hubs I22 directed inwardly toward each other and abutting at their innermost ends. The hubs it? provide seats for the inner races of the anti-friction bearings I24. The hubs 922 are also provided with aligned axial openings adapted to receive a tie bolt or the like lZt.

Now referring to Fig. 4, the rearwardly ex tending arm 55 or" the housing 52 is provided, intermediate its ends, with suitable seats for anti-friction bearings 128 (see Fig. 8). The anti-friction bearings 28 rotatably support aligned hubs its carried by upper and lower sections i3l and i32, respectively, of a guide link Hi3. The upper and lower sections of the guide link i133 are held in assembled relationship along the axis of the bearings I28 by means of a tie bolt its, or other suitable means. As clearly apparent from Fig. 8, the guide link 533 extends generally inwardly of the machine toward the center line thereof and is of less vertical extent at its innermost end whereby the said end may be received between the rearinost end portions of the arms Hi2 and ms. The upper and lower sections of the link L33 are provided, at the said innermost ends, with suitable seats for the anti-friction bearings E24, previously described as being at rearmost ends of the arms it?! and its. If desired, additional bolts or cap screws such as shown at H40 may be employed to further assist in holding the sections i3! and iii-2'. in assembled relation. Suitable dust seals it! are arranged between the arms lii2 and I93 and the link 533 and similar dust seals are provided between the other end of the link I33 and the portion 55 of the housing 52.

Throughout the disclosure thus far all rotary shafts or links have been shown or described as being mounted in anti-friction bearings oi the ball bearing type; however, it is to be understood that other suitable bearings may be employed with equal facility and the invention is not to be limited to the use of ball bearings. For instance, bronze or other sleeve bearings may be employed or suitable roller type bearings may be used.

From the description thus far, it will be clear that rotation of the shaft it, by chain 8 3, will cause the cranks 94 to rotate about their vertical axis and drive the intermediate portions of the arms I82 and H13 in a horizontal circular path. The link I33 guides the rearmost ends of the arms Hi2 and M3 in an arcuate path extending genorally in a fore and aft direction relative to the machine. The movements of the intermediate and rearmost portions of the arms just described result in an orbital movement of the head ii and the pick points carried thereby with the pick points always extending generally forwardly. The orbital movement of the central or foremost pick point of each group is indicated by dotted lines in Fig. 5.

The spacing between the groups of pick points is so chosen that the orbital path of the pick points in the foremost group lit overlaps the orbital path of the pick points in the intermediate group ll'i, which path in turn overlaps that of the rearmost group H8. During operation of the machine the shaft 16 will be rotated in such direction that the pick points move about their orbital paths in the directions indicated by the arrows in Fig. 5 and it will be evident that the points will be in engagement with the material being mined during their movement inwardly toward the longitudinal center line of the machine. During such inward movement each group of pick points will loosen a certain amount of mineral material and move the same inwardly until those points have reached the inner limit of their movement. Such a body of material is represented at I56 in Fig. 5 of the drawings and it will be seen that the configuration oi the head i it is such that the body of material is positioned substantially entirely within the or path of the foremost group of pick points As the cranks 94 continue to rotate, all of the picks will be moved rearwardly away from the mineral material and outwardly to start new cut. During the outward and forward mo ment of the picks of the group H5, those .3 will move around the body of material and will engage the mineral face outwardly of that body of material, thus each cycle of opera of the groups i iii and it? results in those grou. engaging the body of material loosened by next outward group and moving that body of material inwardly toward the center line of the machine and somewhat rearwardly therealcng. In other words, all of the material loosens-:7. each group of pick points it? and its in one cycle of operation is engaged and moved by the next inward group in the next cycle of operai and all of that material will be moved inwa of the machine.

As clearly shown in 5, the innermsst pick of the outer group E E8 moves along an orbital a extending laterally beyond the latera of the machine frame, thereby insui of sufiicient width to accommodate th ly extending frame portion of the is also to be noted that the head lit 1 configuration that it extends across the forcinost end of the housing it when in the position shown in Fig. 3.

Referring now to Fig. 4, the head iii".- is shown as having a bracket E52 bolted or otherwise fas tened to its laterally innermost end, said bracket extending inwardly toward the center line of the machine and carrying a vertical pin defining a vertical pivot axis. The pin i5 3 extends vertically from a position adjacent the bottom of the machine (see Fig. 7) to a position approximately even with the bottom of the attachment portion 63 of the casing 52. The portion of the bracket 552 which supports the pin 55 may be in the form of a pair of spaced ears 5 The pin He l pivotally mounts the front end of pusher plate I58, which has a plurality or" cars l 59 in alignment with the ears of the bracket and through which the pin iii i extends. lhe pusher plate 58 is of a sectional configura ion as shown in Fig. 9 and extends rearwardly and outwardly from the pin i5 i into telescopic sliding engagement with a second pivoted plate I60. The plate ltd may be provided with suitable guide means H32 engaging with complementary edge portions of the plate H558 to define a telescopic structure pivoted at one end to the movable cutter head lid. The plate Hill is pivoted at its rearinost end to the main frame of the machine adjacent tie foremost edge ll of the bottom plate on vertical pin m3. The pivot pin :62 may be supported by suitable bosses H54 and F55 carried by the plates 68 and 2t respectively (Fig. 7). As clearly evident from Figs. 4 and '7, the pusher mechanism comprising plates lbs and ltd is so related to the head lit and the frame plate lib as to define a movable wall substantially impervious to the passage of mineral material at the pivot portions thereof. Thus the bracket 552, the plates l58 and Mill, and the frame plate define one side of a passageway extending from the forward portion of the undercut kerf rearwardly to a position adjacent the forward end of the central conveyor previously described. The bottom surface of the passageway is defined by the floor of the mine and the top of the passageway is partially closed by the plates to and 68. The plate 53, as previously described, does not close the top of this passageway all the way back to the central conveyor, but terminates short thereof to provide an upwardly extending opening at the rear end and through the top of the passageway right adjacent the upwardly movable portions of the central conveyor. It will be evident that the out material removed from the mineral face by the picks H6, H7 and H8 will be cyclically moved inwardly to a position adjacent the front surface of the bracket 52 and upon the following cycle of operation the bracket E52 will move rearwardly and outwardly from such material to a position where the inner face of the plate H58 will engage that material and move it inwardly and rearwardly during the cycles of movement illustrated in Figs. 3, 4 and 5. As successive bodies of material, as shown at 558 (Fig. 5), are moved inwardly by the picks and rearwardly by the plates I58 and IE0, a large mass of cut material will be accumulated in the described passageway and forwardly of the central conveyor. When this large mass of material reaches such a volume as to substantially fill the passageway, successive cycles of operation of the pusher plates lfill and Hill will force the entire mass rearwardly and snugly against the central conveyor whereby upwardly moving flights 32 of said conveyor will engage and carry portions of the mineral material upwardly through the space between said conveyor and the rear edge of the plate 68 to the upper surface of the top plates 26 whence it will be moved rearwardly of the machine along with the material broken down from the vertical face of the material by the picks it and M. This movement of material will be assisted and insured by forward movement of the entire machine, since the cut material in the passageway rests upon the floor of the mine.

If desired, flexible sealing means of any suitable type may be arranged between the top edges of the plates E58 and its and the bottom of the plate so and/or from the brackets l52 to upper arm 552. Such means have not been illustrated in the drawings since they may take many var ious forms.

The operations described in connection with the undercutting head shown in Figs. 3-5 are identical to the operations performed by the undercutting head on the opposite side of the maall;

chine except that those operations are in a reverse direction; however, they still take place in a direction inwardly toward the center line of the machine which lies between the two cutter heads. As also shown in Fig. 5 of the drawings, the orbital path of movement of the -'unermost pick of the group I it extends, at its inner end, across the longitudinal center line of the machine and crosses that center line at points indicated at A and B. Since the machine is constructed symmetrically and the opposite cutter head, shown in dotted lines at C, is constructed to move in an exactly similar path, its innermost pick point will also cross the center line of the machine at the points A and B, thus in suring a continuously cut kerf extending entirely across the working face of the mineral being mined. The cyclical operations of the two cutter heads are, however, not in exact unison since they would then arrive at point A nultaneously and each would then interfere with the movement of the other. To prevent such interference, the movements of the two heads are so timed that the innermost picks of one head, as shown in full lines in Fig. 5, will pass the point A substantially in advance of the time the innermost points of the other head reach point A. The dotted line fragmentary showing of the other pick head in Fig. 5 indicates generally the relationship between the two heads as they approach the innermost points of their orbital paths, and as clearly shown, one head completes its cutting movement somewhat in advance of the other. Since the two cutter heads are driven by sprocket chains and gears from a common shaft (36) the timed relation just de scribed will be maintained for all cycles of operation. The two heads are preferably so timed as to be as nearly in synchronism as possible so that lateral reactions, on the machine, due to the cutting forces involved, will be largely neutralized since the reactions resulting from the movements of the two heads are in opposite directions.

It has been found in actual operation that the two cutter heads need not be out of synchronism with each other but may move through their cycles of operation in exact synchronism when arranged so that the innermost picks on each head do not move in a path overlapping the path of the innermost picks on the opposed head. It has been found that all of the mineral material will be removed from the kerf if the paths of the innermost picks are just short of tangency at their innermost ends. Such an arrangement is contemplated by the present invention and has the advantages of enabling the two cutter heads to be moved in synchronism, thus balancing the lateral forces acting on the machine at all times.

Reference has previously been made to auxiliary or apron conveyors 35 (see Figs. 2, 6, 7 and 11). As previously described, the apron conveyors 35 are trained over pairs of sprockets 34 carried by the shaft 33. A second shaft its is carried by the main frame of the machine rearwardly of the shaft 39 but parallel thereto and is suitably journalled, in bearings (not shown) for free rotation about its axis. The shaft I68 carries pairs of sprockets lid in alignment with the sprockets E l on the shaft 353 and the endless conveyors 35 are trained over the sprockets I76 and then back to the sprockets 34. Figure 2 shows a single shaft E68 extending across the entire machine, but clearly two ii Short aligned shafts could be employed, each being just long enough to accommodate the sprockets no.

Figs. 6 and 11 show the construction of the individual links of the conveyor 35 which comprises a transverse outer plate portion I72, a pair of rearwardly extending ears H4 at the ends of the link and forwardly extending ears lit somewhat inwardly of the ears H4. The forwardly extending ears of each link extend between the ears I'M of the next adjacent link and all ears are provided with aligned openings H3 to receive transverse pins E89. The pins its are effective to pivot adjacent links together and also constitute the means engageable between the teeth of the sprockets 3t and iii! to effect driving and guiding of the conveyors 35. Fig. 6 further illustrates the construction of the outer plate portions H2 which have forwardly and inwardly curved edges 82. The curved edges 582 have an outer surface concentric to the axis of the pin I88 so that the entire conveyor may be flexed around the sprockets while maintaining a continuous outer surface substantially impervious to fine material.

The dimensions of the links of the apron conveyors 35 are such that an exact multiple thereof will extend from the end of one central conveyor flight 32 to the next conveyor flight and the entire length of the conveyor 35 is a multiple of the distance between successive flights 32 of the main conveyor. Certain of the pins its are of a length greater than that of the individual conveyor links and extend inwardly a substantial distance as shown at i8 3 in Figs. 2 and 11. The distance between successive projecting pins 585 is equal to the distance between flights 32 on the central conveyor and they are so related that during movement across the top of the plate 26, in which the conveyors 35 and the central conveyor move in unison, the portions I84 extend inwardly immediately adjacent the rear edges of the ends of the conveyor flights 32. Since the conveyor flights 32 are pivoted to the main chain 23, the portions E84 will be effective to prevent such pivotal movement during the time the conveyors are moving as a unit at the forward portion of the machine. Thus, masses of material moved from one of the conveyors 35 to the central conveyor will not be able to tilt the near end of the flight 32 rearwardly and destroy the conveying function of the central conveyor. As also shown in Fig. '7, the auxiliary or apron conveyors 35 define an upper surface substantially parallel to, but above, the upper surface of the plate 26.

Although a specific type of auxiliary or apron conveyor has been described and shown, it is to be understood that other forms may be employed with equal facility. For instance, it has been found that a screw conveyor extending rearwardly from the shaft 39 may be employed with equal facility and such a conveyor is contemplated within the scope of the present invention. A screw conveyor of this type was readily arranged to be driven, by suitable gearing at its forward end, from the shaft 30 previously described.

The breaking down mechanism comprising the arms 12 and pick points i3 and It includes a plurality of the elements shown in Fig. 1 extending completely across the width of the machine to break down mineral material across a face having a lateral dimension substantially equal to the width of the kerf cut by the undercutting mechanism previously described. It will thus be seen that much of the material broken down by the picks l3 and [4 will fall near the lateral extremities of the machine onto the plate 68 and the apron conveyors 355. As the apron conveyors 35 move rearwardly, such material will be carried toward the rear of the machine thereby. It is contemplated that stationary sweep plates I be fixedly attached to the machine frame and extend angularly across the apron conveyors 35 to force material carried thereby inwardly toward the central conveyor so that all such material will be transferred to the central conveyor before it reaches the rearmost end of the top flight of conveyor 35. Thus, all material broken down will be delivered to the main or central conveyor to be moved to the rear of the machine. Since the apron conveyors do not extend outwardly to the lateral extremities of the machine, it is also contemplated that suitable upwardly and outwardly extending guide plates or the like be provided to catch material that would otherwise fall outside the sweep plates E90 and direct such material to the inside thereof. Such means are not shown in the drawings since they may assume various shapes and configurations not germane to the present invention.

The power for driving the conveyors and undercutting mechanism described herein may be supplied in any suitable or convenient manner. For instance, sprocket chains 295 and it'd (Fig. 2) may extend from sprockets on the shaft 353 rearwardly through the machine frame to a suitable motor or motors. By this arrangement power will be applied to the shaft 3% which in turn will drive the conveyors and the chains t l extending forwardly to the undercutting heads. As an alternative, power may be supplied to the shaft 30 directly through the main conveyor chain 23 since such chain must necessarily pass over a suitable sprocket wheel somewhere at the rear of the machine. Power may be applied directly from the motor to such sprocket wheel or sup porting shaft therefor.

Although a single specific embodiment of the invention has been shown and described, it will be apparent that many modifications may be made in the various elements without depart ing from the scope of the invention. For in" stance, an inwardly extending cleat or cleats may be attached to the forward pusher plate its to further assist in pushing undercut material rearwardly toward the central conveyor. It is understood that the invention is not to be limited to the specific embodiment shown and described, but may be practiced by modifications falling within the scope of the appended claims.

I claim:

1. In a mining machine, a forwardly directed undercutter mechanism comprising, a head nism-- ber, means for moving said head member along an orbital path in a generally horizontal plane, said path extending from. a lateral extremity of said machine inwardly toward the longitudin l centerline thereof then rearwardly then outw ly and forwardly, a plurality of forwardly and inwardly directed pick means carried by head, said pick means being arranged in groups of closely adjacent but vertically spaced picks, said groups being spaced apart in a direction generally parallel to the forward portion of said orbital path, the transverse dimension of said orbital path being at least equal to the spacing between adjacent groups of pick means.

13 2. In a mining machine, a forwardly directed undercutter mechanism comprising, a head member, means for moving said head member along an orbital path in a generally horizontal plane, said path extending from a lateral extremity of said machine inwardly toward the longitudinal centerline thereof then rearwardly then outwardly and forwardly, a plurality of forwardly directed pick means carried by said head, said pick means being arranged in groups, spaced apart in a direction generally parallel to the forward portion of said orbital path, the transverse dimension of said orbital path being at least equal to the spacing between adjacent groups of pick means, said head member including a rearwardly extending portion, said first means including crank means drivingly engag ing said rearwardly extending portion intermediate the ends thereof to move a portion of said rearwardly extending portion around a circular path, and a laterally extending link pivoted to said rearwardly extending portion rearwardly of said crank means and to a fixed pivot.

3. In a mining machine, a forwardly directed undercutter mechanism comprising, a head mem ber, means for moving said head member along an orbital path having a portion adjacent the longitudinal center line of said machine extending inwardly toward said center line and rearwardly, forwardly directed pick means carried by said head, and pusher means pivoted to the innermost side of said head and extending rearwardly to a fixed pivot.

4. A machine as set forth in claim 3 wherein said pusher means comprises a forward vertically extending plate element pivoted to said head member on a vertical axis and a rear vertically extending plate element telescopically engaging said forward plate element and pivoted at its rearmost end on a vertical axis at said fixed pivot.

5. A machine as set forth in claim 3 having a pair of said orbitally movable heads at opposite sides thereof and in which the said fixed pivots are laterally spaced apart, and rearwardly movable conveyor means arranged to receive material moved rearwardly between said fixed pivots.

6. In a mining machine, an undercutting mechanism at the forward end thereof comprising, a frame, a movable head having forwardly extending pick means thereon, vertically spaced arms carried by said head and extending rearwardly therefrom, a housing carried by said frame between said rearwardly extending arms, a pair of vertically spaced cranks rotatably carried by said housing on vertically opposite sides thereof, each of said cranks being pivoted to an adjacent arm intermediate the ends thereof, and means guiding the rearmost ends of said arms along a generally fore and aft path.

'7. A machine as defined in claim 6 wherein the said means for guiding the rearmost ends of said arms comprises a laterally extending link pivoted at one end to the ends of said arms and pivoted at its other end on-an axis fixed relative to said housing.

8. A machine as defined in claim 6 wherein the said housing is fixedly mounted on one side of a forwardly extending hollow frame memher, and drive means extending within said hollow frame member and into said housing to drive said cranks.

9. In a mining machine, a frame having elongated forwardly extending portions constituting the forward end and the lateral extremities of said frame, an undercutting means carried by each of said extending portions on the inner side thereof, said undercutting means being arranged to cut a continuous kerf extending laterally beyond said forwardly extending portions, and plate means extending across the tops of said forward- 1y extending portions and adapted to enter the said kerf and bear against the upper surface thereof, said undercutting means being orbitally movable in a horizontal plane to cut material being mined and move said material toward the longitudinal center line of said machine, pusher means driven by said undercutting means to engage said material moved by said undercutting means and move the same inwardly and rearwardly of said machine below said plate means, and conveyor means arranged to receive material moved by said pusher means. 7

10. In a mining machine, a frame having a forward portion adapted to enter a kerf in mineral material, said forward portion including a substantially horizontal plate extending completely transversely across said machine and defining the uppermost portion of said forward portion, said plate being adapted to engage the downwardly facing surface of said kerf and having a rear terminal edge extending transversely of and sub stantially completely across said machine, break" down means carried by said frame and cyclically movable downwardly to a position closely adjacent but slightly rearwardly of said terminal edge whereby to break down mineral material above said kerf which overhangs said terminal edge.

11. In a mining machine, a frame having a forward portion adapted to enter a kerf in min eral material, said forward portion including a substantially horizontal plate extending completely transversely across said machine and de fining the uppermost portion of said forward portion, said plate being adapted to engage the downwardly facing surface of said kerf and hava rear terminal edge extending transversely of and substantially completely across said machine, break-down means carried by said frame and cyclically movable downwardly to a position closely adjacent but slightly rearwardly of said terminal edge whereby to break down mineral material above said kerf which overhangs said terminal edge, and a second substantially horizontal plate carried by said frame below said first plate and extending rearwardly from said terminal edge and continuously across said machine in a transverse direction.

12. In a mining machine, a frame having laterally spaced forwardly extending portions, a plate extending across the tops of said portions and attached thereto, a housing carried by each extending portion on the inner side thereof and attached thereto at longitudinally spaced points, each housing being attached to said plate at a point spaced substantially inwardly of said ex-- tending portions of said frame, movable undercutting picks, said picks being mounted on and driven by means carried by said housings.

13. In a mining machine, a forwardly extending transverse plate spaced above the bottom of said machine and having a rear terminal edge, an endless conveyor extending longitudinally of said machine and mounted for movement along a path extending forwardly adjacent the bottom of said machine then upwardly slightly to the rear of said terminal edge then rearwardly, undercutting means carried by said machine below and forwardly of said plate, and means below said plate for guiding and moving material to the upwardly moving portion of said conveyor.

14. A machine as defined in claim 13 wherein said last-named means comprises laterally spaced vertical side Walls defining a passageway therebetween, opposed portions of said side walls being pivoted on vertical axes, and means for cyclically swinging said portions about said axes in an inwardly and rearwarcuy direction to move material therebetween toward said conveyor.

References Cited in the file Of this patent I UNITED STATES PATENTS Number Name Date 538,210 Dierdorfi Apr. 23, 1895 630,388 Miller Aug. 8, 1899 700,628 Dierdorfi May 20, 1902 1,143,897 Flexner et a1 June 22, 1915 Number 15 Number Name Date Joy June 16, 1919 Holmes Dec. 15, 1931 Hauge Oct. 25, 1932 Range Apr. 11, 1933 Cartlidge Sept. 21, 1943 Arentzen Jan. 4, 194% Miller Feb. 6, 19 15 Tibbals June 10, 1947 Merchant July 15, 1947 Levin Aug. 22, 1950 Merchant Nov. 21, 1950 FOREIGN PATENTS Country Date Germany Aug. 8, 1935 Great Britain Mar. 29, 19-19 

